Forced and natural draft cooling arrangement for refrigerator



June 2, 1964 H. M. ULLSTRAND 3,135,102

FORCED AND NATURAL DRAFT COOLING ARRANGEMENT FOR REFRIGERATOR FiledMarch 2, 1962 4 Sheets-Sheet 1 F/GJ I NVEN TOR.

@ATTORNEY Juney 2, 1964 H. M. ULLSTRAND FORCED AND NATURAL DRAFT COOLINGARRANGEMEJNT FOR RFRIGERATOR 4 Sheets-Sheet 2 Filed March 2, 1962INVENTOR. @ma

@ATTORNEY June 2, 1964 H. M. ULLSTRAND 3,135,102

FORCED AND NATURAL. DRAFT COOLING ARRANGEMENT FOR REFRIGERATOR FiledMarch 2, 1962 4 Sheets-Sheet 3 INVENTOR.

,wfmfw ff@ June 2, 1964 H, M, ULLSTRAND 3,135,102

FORCED AND NATURAL DRAFT COOLING ARRANGEMENT FOR REFRIGERATOR FiledMarch '2, 1962 4 sheets-shed 4 INVENTOR.

A; ATTORNEY l United States Patent 3,135,102 FRCED AND NATURAL DRAFTCOOLING AGEMENT FR REFRIGERATOR Hugo Malcolm Ullstrand, Stockholm,Sweden, assignor to Alrtiebolaget Electrolux, Stockholm, Sweden, acorporation of Sweden Filed Mar. 2, 1962, Ser. No. 176,959 Claimspriority, application Sweden Mar. 3, 1961 10 Claims. (Cl. 62-419) Myinvention relates to refrigeration, and more particularly concernscooling of the thermally insulated interior of a refrigerator by forcedand natural draft circulation of air.

It has been the practice heretofore to effect cooling of a thermallyinsulated compartment of a refrigerator by circulating air in thermalrelation with a cooling element by forced draft with the aid of a fan,so that the temperature developed in the storage compartment willapproach the temperature of the cooling element. The cooling element mayform a part of refrigeration apparatus operated by a source of heat likea fluid fuel burner, for example, and the fan arranged to be driven byan electric motor. If the source of electrical supply should becomeunavailable for driving a` fan motor in refrigeration apparatus of theheat-operated type, the apparatus still will operate normally tomaintain the cooling element at its desired low temperature.

The fan for circulating air by forced draft often is located exteriorlyof the storage compartment in a passageway through which air flows fromand back to the compartment, and the cooling element is positioned inthe passageway for cooling the air flowing in thermal relationtherewith. This positioning of the cooling element would be objectablein heat-operated refrigeration apparatus, because the cooling elementwould be removed from the compartment and could not be employedeiliciently for cooling the compartment if the fan motor should becomeinoperable.

The object of my invention is to provide an improvement for cooling arefrigerator compartment whereby air will be. circulated by forced draftover a cooling'eleinent by a motor-driven fan when the fan motor isoperable, and, if the fan motor should become inoperable because of thefailure of the source of electrical supply the cooling element isemployed to induce natural circulation of air in thermal relationtherewith.

The invention, together with the above and other 0bjects and advantagesthereof, will be more fully understood from the following descriptionand accompanying drawings forming a partA of this specification, and inwhich:

FIG. l is a front elevation, partly broken away, of a refrigeratorembodying my invention, the front doors being omitted to simplify thedrawing;

FIG. 2 is a side view, partly in section, of the refrigerator shown inFIG. l;

. FIGS. 3 and 4 are views similar to FIGS. 1 and 2, respectively, toillustrate the operation of the refrigerator moreV clearly; i

FIG. 5 is a front elevation of an evaporator or cooling element of theform illustrated in FIGS. 1 to 4, inclusive; Y

FIG. 6 is a top plan view of the evaporator or cooling element shown inFIG. 5;

FIG. 7 is a fragmentary perspective View of details shown in FIGS. l and2; and

FIG. 8 is a fragmentary sectional view taken at line 8--3 of FIG. 1.V

Referring to FIGS. l and 2, I have shown my invention embodied in ahousehold refrigerator comprising a cabi- ICC net 1t) having innershells 11 and 12 supported one above the other within an outer shell 14and insulated therefrom and from one another with any suitableinsulating material 15. The insulation between the inner shells 11 and12 and the shell walls against which it bears defines a horizontalpartition 16 which thermally segregates top and bottom compartments 17and 18 dened by the inner shells 11 and 12, respectively.

The top compartment 17 serves as a thermally insulated freezer space andthe bottom compartment 18 as a space for storing foods at a highertemperature than that inthe top compartment 17 and preferably at atemperature above 32 F. Access to the top and bottom compartments 17 and18 is afforded at front openings which are adapted to be closed byinsulated doors 19 and 20 hinged in any suitable manner (not shown) atthe front of the cabinet 10.

The top freezer space 17 is arranged to be cooled by a cooling elementor evaporator 21 and the bottom food storage space 1S is arranged to becooled byV a cooling element or evaporator 22. The cooling elements 21and 22 desirably form low and higher temperature sections of a coolingunit of refrigeration apparatus of any suitable type. As shown, therefrigeration apparatus may be of a uniform pressure absorption type,generally as described in my United States Letters Patent No. 2,635,437,granted April 21, 1953. In apparatus of this type, the cooling elements21 and 22 are connected by conduits (not shown) to other parts of therefrigeration apparatus 23 at the rear of the cabinet 10. Parts of therefrigeration apparatus have been ommitted and other parts, like thegenerator 24 and condenser 2S, have been shown only diagrammatically, acomplete illustration of the apparatus not being necessary for anunderstanding of my invention.

Parts of refrigeration apparatus of the absorption type, whose relativepositions are substantially fixed, usually are formed of iron or steelwhen ammonia and water are employed as the refrigerant and liquidabsorbent, respectively. Accordingly, the piping for the coolingelements 21 and 22, which form a unitary part of the refrigerationapparatus 23, may be formed ofV ferrous metal also. The rear wall of thecabinet 10 is formed with an opening through which the cooling elements21 and 22 are inserted into the interior of the cabinet 10, such openingbeing closed by an insulated closure member 26 removably secured to thecabinet in any suitable manner and through which extend the conduits(not shown) connecting the cooling elements 21 and 22 and other parts ofthe refrigeration apparatus 23. A frame (not shown) may be provided atthe rear of cabinet 10 upon which the refrigeration apparatus 23 ismounted. The refrigeration apparatus is adapted to be operated by asuitable source of heat, such as a fluid fuel burner 27, which isarranged to project its ame into the lower end of a liue 28 extendingthrough the generator 24.

A drain pan 29 is provided in the bottom of the inner liner 11 below thecooling element 21 for collecting water dripping therefrom, as duringdefrosting, for example. The water drains from pan 29 through a tube 30having a attended lower end 31 disposed above asecond drain pan 32mounted in any suitable manner below the cooling element 22. 'Water inpan 32 iiows therefrom by gravity through a conduit 33 extending throughthe rear wall of the cabinet 10 and is discharged into a pan orcollecting vessel 34 in good heat conductive relation with a heatedconduit 35 of the refrigeration apparatus. With this arrangement, watercollected in vessel 34, as during defrosting, is effectively evaporated.

The flattened lower end 31 of tube 30, which is normally closed to sealthe top and bottom compartments 17 and 18 from one another, may be.formed of soft resilient material like rubber, for example. When theliquid head in the tube 30 becomes sufficiently great, the softresilient material yields to the force developed by the liquid columnand.the lower end 31 of the drain tube opens to allow water to passtherethrough during periods when defrosting is being effected, forexample, and the temperature at the immediate vicinity of the drain tubeis above 32 F.

Each of the cooling elements 21 and 22 is in the form of a looped coilinto which a refrigerant fluid, such as ammonia, is introduced fordownward flow therethrough. The refrigerant evaporates in the coolingelements into an inert gas, such as hydrogen, to produce a refrigeratingeffect. The cooling elements are similar, cooling element 21 includingtwo parallel banks 21a and 2lb of essentially straight tubes disposedone above the other, the tubes in the banks 21a and 2lb dipping downwardslightly in opposite directions from the horizontal. The tube banks 21aand 2lb, which are spaced from one another, form a vertical passage 36therebetween. The ends of the tubes in the tube banks are connected byU-bends, the lower end of each tube in one tube bank being connected tothe upper end of a tube in the other tube bank to provide a continuouslyelongated path of flow for the refrigerant uid. As seen in FIG. 5, thebottoms of the tubes in each tube bank are indented at spaced intervalsat 37 whereby shallow pools of refrigerant can form in its downward pathof flow through the coil. It will be observed in FIG. that verticallyextending planes perpendicular to the longitudinal axes of the straighttubes in the two tube banks 21a and 2lb are inclined at acute angles inopposite directions from the same given vertical plane.

The cooling elements 21 and 22 are disposed in the rear of thecompartments 17 and 18 and are employed to cool air flowing in thermaltransfer relation therewith. Although the straight tubes of the tubebanks of the cooling elements are fnless, the looped coil of eachcooling element is of adequate length and of sufficient size to providea relatively extensive heat transfer surface that is sufficient to coolair in thecompartments 21 and 22 in a manner which will be describedpresently.

The cooling elements 21 and 22 are concealed from View by the frontimperforate walls 38a, 39a and spaced end walls 38h, 39b and 38C, 39e ofthree-sided casings 38, 39. The three-sided casings 38 and 39, togetherwith the rear walls of the inner shells 11 and 12, define verticallyextending passages 38d, 39d in which the cooling elements 21 and 22 aredisposed. The front casing Walls 38a, 39a may either be spaced from orheat conductively connected to the tube banks of the cooling elements21, 22 which are closely adjacent thereto.

Suitable fans 40, 41 having air inlets 40a, 41a and air outlets 4011.41b are provided for circulating air in the compartments 17 and 18 byforced draft. The fans 40, 41 are disposed outside the passageways 38d,39d at the rear of the compartments 17, 18 and are arranged to be drivenby electric' motors which may be located either in the insulated closuremember 26 or at the rear of the cabinet 10. As seen in FIG. 8, anelectric motor 42 connected by a shaft 43 to drive the fan 40 is mountedin any suitable manner within the closure member 26, and an electricmotor 44 connected by a shaft 45 to drive the fan 41 is mounted in anysuitable manner to the rear wall of the closure member 26 outside thecabinet 10. If desired, the motors 42 and 44 may both be located withinthe closure member 26 or outside the cabinet 10. As seen in FIG. 8, theelectrical motors 42 and 44 are respectively connected to c onductors 60by conductors 42a and 44a, the conductors 60 in turn being connected toa suitable source of electrical supply.

It will now be understood that the cooling elements 21, 22 form thecooling unit of refrigeration apparatus which may be operated by asource of heat like the fluid fuel burner 27, and that the fans 40, 41,which circulate air by forced draft in the compartments 17, 18, aredriven bythe electric motors 42, 44. If the source of electrical supplyshould become unavailable for driving the fan motors 42, 44, normaloperation of the refrigeration apparatus still can be effected by theiluid fuel burner 27 to maintain the cooling elements 21, 22 at theirdesired low temperatures.

In Vaccordance with my invention, the cooling elements 21, 22 andcasings 38, 39 and fans 40, 41 are related to one another in such mannerthat the air will be circulated by forced draft over the coolingelements 21, 22 by the fans 40, 41 when the fan motors 42, 44 areoperable to promote cooling of the compartments 17, 18; and, if the fanmotors 42, 44 should become inoperable because of the failure of thesource of electrical supply, the cooling elements 21, 22 can be employedito induce natural circulation of the air in thermal relation therewithto promote cooling of the compartments 17, 18.

Referring to FIGS. 1 and 7, the air outlets 40b, 41b of the fans 40, 41are connected to the casing end walls 38b, 39b in communication withopenings therein, one of which is shown in FIG. 7 at 38e. The end walls38]?, 39b are imperforate except for the openings to which the fan airoutlets 4011, 4111 are connected, such openings being closely adjacentto the top edges of the end walls. The front walls 38a, 39a areimperforate whereas the end walls 38C, 39C removed from the fans 40, 41are provided with elongated slots 46. The casing 38 is also providedwith a top wall 38f having elongated slots 47. The casing 38 is open atthe bottom at 48, and the casing 39 is open at both the top and bottomat 49 and 50, respectively.

When the fans 40 and 41 are being operated, air in the compartments 17,18 is drawn into the fan inlets 40a, 41a at regions which are removedfrom the bottom openings 48, 5t) of the passageways 38d, 39d. The air isdischarged at a higher pressure from the fan outlets 4Gb, 41b into thecasings 38, 39 at regions above the bottom openings of the passageways38d, 39d. The air introduced at a relatively high velocity into thecasings 38, 39 flows horizontally across the compartments 17, 18 inthermal relation with the spaced tube banks 21a and 2lb, the inclinationof the two tube banks at acute angles in opposite directions from thesame given vertical plane functioning to stir and promote e'icientcooling of the air. Further, successive turns of the looped coolingelement coils 21 and 22 lare longitudinally displaced or offset withrespect to one another, as indicated at 51, 52, 53 and 54 in FIG. 5.With this coil construction, openings are formed between adjacent turnsat the ends of the coils, as indicated at 55 and 56 in FIG. 6. The endopenings 55 and 56 of the coils provide a multiplicity of paths of owfor circulating air so that air will flow in intimate physical contactwith all surface regions of the cooling elements or coils 21 and 22.

With this construction, the fact that the coils 21 and 22 are finlessdoes not impair their ability to effect efficient cooling of air,because the openings 55 and 56 at the ends of the coils serve as inletand outlet openings to allow the high velocity air discharged from thefans 40 and 41 to enter and leave the vertical passages within thecoils, one of which is shown at 36 in FIG. 6. Cool airis discharged fromthe casing 38 through the openings 46 in end wall 38e, openings 47 intop wall 381, and from the bottom opening 48, as indicated by the arrowsin FIGS. l, 2 and 7. Cool air is discharged from the casing 39 throughopenings in the end wall 39C and from the top and bottom openings 49 and50, respectively, as indicated by the arrows in FIGS. l and 2.

If the fan motors 42, 44 should become inoperable because of failure ofthe source of electrical supply, the cooling elements 21, 22 can beemployed to induce natural circulation of air in the compartments 17,18. Air cooled by thermal transfer with the cooling elements 21, 22flows downward in the compartments 17, 18 from the bottom openings 48,50 to replace warmer air which flows upward and enters the casing 38through the openings 47 in its top wall 38], and enters the casing 39through its top opening 49. This natural circulation of air, which isindicated by the arrows in FIGS. 3 and 4, is due to the difference inspecific weights of air at different temperatures. It will be observedthat under this operating condition the fans 40, 41 are out of the pathof flow of the air in the passages 38d, 39d in the casings 38, 39.

In view of the foregoing, it will now be understood that if the fanmotors 42, 44 should become inoperable, the cooling elements Z1, 22nevertheless can be employed to effect cooling of compartments 17, 18 byinducing natural draft circulation of air therein. While natural draftcirculation is not as effective as the forced draft circulation of airprovided by the fan motors 42, 44, adequate cooling of the compartmentsis promoted to prevent food spoilage even if the fan motors 42, 44should remain inoperable for relatively long periods of time.

Modifications of the embodiment of the invention I have illustrated anddescribed will occur to those skilled in the art, so that I desire myinvention not to be limited to the particular varrangement set forth.For example, the front walls 38a, 39a of the casiugs 38, 39 may beformed with openings if desired. Also, the closure member 26 at the rearinsulated wall of the cabinet may be formed with recesses at its innerwall surface in which the cooling elements 21, 22 may be positioned.With such arangement, the cooling elements Z1, 22 will occupy less spacein the compartment 17, 18. It will be observed in the preferredembodiment that the overall depth of the refrigeration apparatus is notunduly great. This is a distinct advantage in absorption refrigerationapparatus of the kind illustrated and described for the reason that whenthe cooling unit is relatively near the parts of the refrigerationapparatus outside the cabinet and not laterally offset to a markeddegree, crating and shipping problems are simplified. Therefore, Iintend in the claims to cover all those modifications which do notdepart from the spirit and scope of my invention.

I claim:

l. In a refrigerator including a cabinet having a thermally insulatedinterior, structure defining a ventically extending passageway having afirst opening at a first level and a second opening at a second-higherlevel, both the first and second openings of the passageway being incommunication with the interior lof the cabinet, heatoperatedrefrigeration apparatus comprising a cooling element disposed in thepassageway, means including a motor-driven fan outside of the passagewayhaving an air inlet in communication with the interior of the cabinet ata region removed from the first opening for withdrawing air from thecabinet interior and an air outlet in communication with the passagewayfor discharging the air over the cooling element in contact therewithand inducing forced circulation of cooled air in the interior of thecabinet, means for connecting the motor-driven fan to a source ofelectrical supply, the heat-operated refrigeration apparatus beingoperable when the motordriven fan is inoperable due to failure of thesource of electrical supply, and the passageway structure and coolingelement therein functioning to induce natural circulation of air in theinterior of the cabinet responsive to cessation of operation of themotor-driven fan.

2. A refrigerator as set forth in` claim l in which the air outlet ofthe fan is in communication with the passageway by a connection wherebyall of the air discharged from the fan is introduced into the passagewayat a region above the first opening.

3. A refrigerator as set forth in claim 1 in which the outlet of the fanis constructed and arranged to discharge air therefrom in an essentiallyhorizontally extending direction across the passageway at a level abovethe first opening thereof.

4. A refrigerator as set forth in claim 1 which includes thermallyinsulated walls defining a compartment forming the thermally insulatedinterior, the thermally insulated walls including a rear wall andlateral side walls,

the cooling element extending horizontally between the lateral sidewalls adjacent to the rear wall, the outlet of the fan being constructedand arranged to discharge air therefrom in an essentially horizontaldirection across the passageway in contact with the cooling element, andthe structure defining the passageway being apertured at the regiontoward which air is horizontally discharged across the passagewaywhereby circulation of air is induced by forced draft in the cabinetinterior with air flowing through the apertured region and both thefirst and second openings of the passageway.

5. A refrigerator as set forth in claim 4 in which the cooling elementcomprises a plurality of banks of tubes spaced from one another, saidtubes extending horizontally across the passageway, the tubes ofadjacent banks being inclined downward in opposite directions from thehorizontal whereby air flowing over the tubes is divided into amultiplicity of paths of ow in intimate contact with the tubes.

6. A refrigerator as set forth in claim 4 in which the cooling elementcomprises a looped coil having essentially straight portions andconnecting bends defining a vertically extending passage, the straightportions extending across the passageway, and successive turns of thecoil being staggered or offset with respect to one another lengthwise ofthe straight portions to form openings between adjacent turns at theconnecting bends to promote movement of air into and from the passagewithin the looped coil during its fiow across the passageway from thefan outlet.

7. A refrigerator as set forth in claim 1 which includes thermallyinsulated walls having an inner liner defining a compartment forming thethermally insulated interior, the cooling element comprising a loopedcoil disposed adjacent to the liner, the passageway being formed by acasing mounted on the liner about the cooling element, the casing havinga front wall and end walls, the fan outlet being connected to one Vendwall at an opening therein, the opposite end wall of the casing beingapertured, and the casing having openings at the top and bottom servingas the first and second openings of the passageway.

8. In a refrigerator including a cabinet having a therrnally insulatedinterior, structure defining a vertically extending passageway having afirst opening at a first level and a second opening at a second higherlevel, both the rst and second openings of the passageway being incommunication with the interior of the cabinet, heatoperated absorptionrefrigeration apparatus comprising a plurality of parts including a heatreceiving part and a cooling element in which refrigerant fluidevaporates in the presence of an inert gas, means including a fluid fuelburner for heating the heat receiving part, the cooling element beingdisposed in the passageway, means including a fan outside the passagewayhaving an air inlet in Colnmunication with the interior of the cabinetat a region removed from the first opening for withdrawing air from thecabinet interior and an air outlet in communication with the passagewayfor discharging the air over the cooling element in contact therewithand inducing forced circulation of cooled air in the interior of thecabinet, an electric motor for driving the fan, means for connecting thefan motor to a source of electrical supply, the heat operated absorptionrefrigeration apparatus being operable when the fan motor is inoperabledue to failure of the source of electrical supply, and the passagewaystructure and cooling element therein functioning to induce naturalcirculation of air in the interior of the cabinet responsive tocessation of operation of the electric motor.

9. A refrigerator as set forth in claim 8 in which the parts of therefrigeration apparatus are essentially irnmovable with respect to oneanother and one of the thermally insulated walls is formed with anopening through which the cooling element is insertable into andremovable from the compartment, a thermally insulated closure member forclosing the opening, the closure member forming a unitary part of therefrigeration apparatus,

the passageway structure including a casing mounted on the inner surfaceof the closure member about the cooling element, and the top and bottomof the casing having openings serving as the rst and second openings ofthe passageway.

10. In a refrigerator including a cabinet having a plurality ofthermally insulated compartments one above the other, structure in eachcompartment dening a vertically extending passageway having a firstopening at a rst level and a second opening at a second higher level,both the rst and second openings of each passageway being incommunication with the compartment in which it is located,heat-'operated absorption refrigeration apparatus comprising a heatreceiving part and rst and second cooling elements in which refrigerantfluid evaporates in the presence of an inert gas, means including afluid fuel burner for heatingthe heat receiving part, each coolingelement being disposed in a different one of the passageways,meansincluding fans outside thev passageways each having an air inlet incommunication with a different one of the compantments for withdrawingair therefrom and an'air outlet incommunication with a different one ofthe passageways for discharging air over the cooling element therein andindependently inducing forced circulation of cooled air in thecompartments, the air inlet of the fan in each compartment being at aregion removed from the rst opening of the passageway therein,l anelectric motor for driving each fan, means for connecting the fan motorsfto a source of electrical supply, the heat-operated absorptionrefrigeration apparatus being operable when the fan motors areinoperable due to failure of the source of electrical supply, and thepassageway structure and cooling element in each compartment functioningto induce natural circulation of air therein responsive to cessation ofoperation of the electric motors.

References Cited in the leof this patent i UNITED STATES PATENTS2,285,945 Rundell June 9, 1942 2,310,875 Siedle Feb. 9, 1943 2,597,813Piper May 20, 1952 2,982,115 Wurtz et al. May 2, 1961 3,004,400 Mannetal. Oct. 17, 1961

1. IN A REFRIGERATOR INCLUDING A CABINET HAVING A THERMALLY INSULATEDINTERIOR, STRUCTURE DEFINING A VERTICALLY EXTENDING PASSAGEWAY HAVING AFIRST OPENING AT A FIRST LEVEL AND A SECOND OPENING AT A SECOND HIGHERLEVEL, BOTH THE FIRST AND SECOND OPENINGS OF THE PASSAGEWAY BEING INCOMMUNICATION WITH THE INTERIOR OF THE CABINET, HEATOPERATEDREFRIGERATION APPARATUS COMPRISING A COOLING ELEMENT DISPOSED IN THEPASSAGEWAY, MEANS INCLUDING A MOTOR-DRIVEN FAN OUTSIDE OF THE PASSAGEWAYHAVING AN AIR INLET IN COMMUNICATION WITH THE INTERIOR OF THE CABINET ATA REGION REMOVED FROM THE FIRST OPENING FOR WITHDRAWING AIR FROM THECABINET INTERIOR AND AN AIR OUTLET IN COMMUNICATION WITH THE PASSAGEWAYFOR DISCHARGING THE AIR OVER THE COOLING ELEMENT IN CONTACT THEREWITHAND INDUCING FORCED CIRCULATION OF COOLED AIR IN THE INTERIOR OF THECABINET, MEANS FOR CONNECTING THE MOTOR-DRIVEN FAN TO A SOURCE OFELECTRICAL SUPPLY, THE HEAT-OPERATED REFRIGERATION APPARATUS BEINGOPERABLE WHEN THE MOTORDRIVEN FAN IS INOPERABLE DUE TO FAILURE OF THESOURCE OF ELECTRICAL SUPPLY, AND THE PASSAGEWAY STRUCTURE AND COOLINGELEMENT THEREIN FUNCTIONING TO INDUCE NATURAL CIRCULATION OF AIR IN THEINTERIOR OF THE CABINET RESPONSIVE TO CESSATION OF OPERATION OF THEMOTOR-DRIVEN FAN.